(1) Field of the Invention
The present invention relates to underwater targeting and tracing systems and more specifically to systems and methods for controlling and utilizing supercavitating projectile dynamics to produce a distinctive radiated noise signal.
(2) Description of the Prior Art
There exists a need for accurate localization of underwater targets for a variety of underwater systems. The basic means of identification of an underwater object or target usually relies on the transmission of an acoustic signal from a fixed location and processing of a return echo at that same location. As in the case of an in-air tracer bullet, when launching a plurality of high velocity underwater projectiles against a target, it would be desirable to trace the path of a number of such projectiles so as to localize the proximity of the projectile stream on the intended target.
The art for tracing underwater high speed objects previously has been limited to measuring the speed of relatively small metallic objects which travel relatively closely to a magnetic pickup. For larger, high speed, underwater projectiles, supercavitating underwater vehicles have been proposed for use. The conditions for supercavitation are known in the art. Supercavitation allows for higher speeds to be sustainable by reducing skin friction drag to a great extent at such higher speeds.
Proposed means for tracking larger underwater high speed objects, such as a supercavitating vehicle, rely on a number of hoops aligned on a range in the anticipated path of the high speed projectile. The hoops are sufficiently large relative to the size of the projectile and anticipated path. Each hoop contains a number of independent hydrophones. The signals from the hydrophones may be analyzed to accurately determine position and track of an underwater projectile along the plane of each hoop. The system may be used as a fixed range or as a mobile range in a remote location. However, since the hoops must be placed in the anticipated path of the projectile, such means do not aid in localizing the proximity of a projectile stream on an intended target.
Systems and methods are needed that can produce radiated acoustic signals from the projectile in the near vicinity of the targeted object. In order to properly distinguish the radiated acoustic signals from the projectile so as to accurately track its path, the signals can be designed to be either greater in amplitude or easier to characterize than would a transmitted signal from the receiver or target location.
By providing a distinguishable acoustic signal, the systems and methods can provide better resolution of underwater vehicle position and improved tracking of an underwater object. The ability to more effectively target underwater objects moving at high speed may be enhanced through better resolution of underwater objects and tracks in poor acoustic environments.
The distinguishable acoustic signal of the systems and methods herein can lead to decreased signal processing requirements to achieve a desired target resolution and a better ability to resolve multiple targets. Accordingly, the systems and methods may be particular effective in conjunction with projectile-based terminal defense systems, mine clearance systems, stand alone gun systems for augmenting existing targeting systems, and the like.